1. Technical Field
The present invention generally relates to communication systems, such as cellular communication networks, and particularly relates to a method and apparatus for canceling partially known interference using transmit diversity based interference cancellation (TDIC).
2. Background
Wireless communication networks commonly employ spatial reuse for improved network capacity. With spatial reuse, geographically separate transmitters reuse the same channelization resources (i.e., spreading codes, frequencies, and or times) to transmit different information to different users. Not uncommonly, the receiver targeted by one transmitter moves into a service area where another transmitter interferes with it. That is, the targeted receiver's reception of desired symbols from a first transmitter is interfered with by its reception of interfering symbols from a nearby or adjacent second transmitter.
Such scenarios arise, for example, in relay-based communication systems wherein a first transmitter transmits directly to a first targeted receiver and relays transmit information for a second targeted receiver to a given relay station. In turn, that relay station transmits the relayed transmit information to the second targeted receiver. Depending upon geography and the location of the first targeted receiver, transmissions from the relay station may significantly interfere with its reception of desired information from the first transmitter. Of course, the same or similar interference scenarios can arise in non-relay communication networks, as well.
One mechanism to combat such interference involves strategic scheduling of transmission times across or between potentially interfering transmitters. However, doing so obviously adds to network complexity because of the need for increased coordination between the transmitters. Such operation also reduces the spectral efficiency of the network, as some transmitters forego transmission to one or more of their supported receivers at strategic times.